In an internal combustion engine for an automobile, there is performed a control of the internal combustion engine in which the internal combustion engine is stopped automatically when the automobile decelerates or stops to improve the fuel consumption or the like, and when a starting operation such as pressing the accelerator pedal is performed, the internal combustion engine starts automatically, that is, a so-called economy running control (hereinafter referred to as “eco-run control”) (see, for example, Japanese Patent Laying-Open No. 10-47104).
When an engine start is performed in the internal combustion engine in which the eco-run control is performed, if a crankshaft is rotated at a predetermined position by a starter motor and fuel injection is performed in a specific cylinder so as to start the engine with combustion torque of the cylinder, a time period required for the engine start becomes longer, which makes a rapid engine start difficult.
In view of the above, there is disclosed a technique for shortening the time required for an engine start by detecting a cylinder in an expansion stroke when the engine is in a stopped state by the eco-run control, and when the engine starts, fuel is injected into the cylinder directly so as to generate combustion torque (see, for example, Japanese Patent Laying-Open No. 2001-342876).
When an internal combustion engine stopped by the eco-run control is caused to start, it is possible to perform an engine start by injecting fuel directly into a cylinder reaching an expansion stroke at the time of engine stop and using the combustion torque generated by the combustion of the fuel. However, the internal combustion engine is in an engine stopped state at the time of injecting the fuel, so there is no disturbance caused by the air current inside the cylinder, whereby the injected fuel is less likely to be diffused uniformly within the cylinder. Accordingly, there may be a case where too dense portions are caused locally in the air-fuel mixture prepared in the cylinder, causing an increase in unburned fuel components, and worsening of emission such as generation of black smoke.